Electrical heating appliance



July 28, 1931. H. N. SHAW ELECTRICAL HEATING APPLIANCE Filed Dec. 3, 1925 3 Shebts-Sheet 1.,

Ewan/Mom Wot/wag July 28, 1931. H. N. SHAW ELECTRICAL HEATING APPLIANCE Filed Dec. 3, 1925 3 Sheets-Sheet 2 g m 6 a w v a a 9 H m 24w- H. N. SHAW ELECTRICAL HEATING APPLIANCE July 28, 1931.

Filed Dec. 3, 1925 3 Sheets-Sheet 3 a p 2 v .3 lmA 7 mm L P 4 7w. 0H ah z m m 0 W 6 m7 2 m Cl m m iE l Patented July 28, 1931 UNITED STATES PATENT OFFICE HAROLD N. SHAW, F MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO GLOBAR CORPORATION, OF NIAGARA FALLS, NEW YORK, A CORPORATION OF NEW YORK ELECTRICAL HEATING APPLIANCE Application filed December The present invention relates in general to electrical apparatus including one or more resistance units of a type adapted for the production and emission of radiant energy in the form of heat or light or a combination of both effects; and the invention has particular relation to apparatus of this type wherein the desired effects are produced Wholly through radiation from the source of rays or partly through direct radiation and partly through reflection. A particular application of the invention of extreme utility is in connection with the production and emission of a. combination of heating and lighting effects or other effects associated with heat waves of a wave length outside of the limits of the ordinary spectrum scale, this latter class of apparatus having its more particular use in connection with therapeutics or the treatment of physical tissues.

Features of the present invention are concerned with the production and eflicient utilization of a suitable resistance unit of the selfsustaining type and the design and construction of simple, eflicient and economical mountings for such resistance units. In electrical heating apparatus utilizing preferred types of heating units adapted for the production of relatively high operating temperatures, and also heating or lighting effects dependent upon the radiation of rays of special character for utilization for therapeutic and other purposes, it is especially desirable, and it has heretofore been rather diflicult to satisfactorily maintain the resistance heating element in mechanically and electrically operative position in the heating apparatus. The high temperatures ordinarily present at the point of engagement or contact between the heating element and conductive terminal or mounting devices heretofore used have caused deleterious oxidation or scaling of the metal of the terminal and consequent deterioration of the contact.

In accordance with the present invention, an electrical heatingappliance is provided which is especially adapted for producing and radiating or reflecting heat waves or a combination of heat and light waves of special character, and utilizes as a heat or light 3, 1925. Serial No. 72,881.

source a self-sustaining or rigid element, preferably provided with terminals more highly conductive than the body portion and mounted in a yielding and readily detachable manner between contact terminal devices which serve to mechanically support the elements in operative position and electrically connect the same in circuit through engagement with the end surfaces of such elements. These heating elements and their combined mechanical and electrical mountings may, in accordance with the present invention, be mounted on a single plug or like support adapted for ready mechanical and electrical attachment or securing in operative position in a reflector or like carrier.

It is an object of the present invention to provide an electrical appliance of improved design and construction embodying a selfsustaining resistance element and terminals therefor mounted upon a single support or base and effective to maintain the resistance element in mechanically and electrically operative position through butt-end engagement therewith.

It is a further object of the present invention to provide an electrical heating appliance embodying one or more self-sustaining resistance elements and terminals therefor mounted on a support in combinaton with a reflector or other carrier in which the base is mounted in a readily detachableand replaceable manner.

It is a further object of the present invention to provide an electrical heating appliance of the character indicated wherein the heating element has terminal portions which are more highly conductive than the body portion of the resistance element.

These and other objects andadvantages are attained by the present invention, various novel features of which will be apparent I unit embodying features of the present invention.

Fig. 2 is a view generally similar to Fig. 1, but with parts shown in perspe tive, of a modified form of electrical heating appliance.

Fig. 3 is a view in tragmental sectional elevation of a further modification of the invention.

Figs. l and 5 are sectional plan views taken in the planes of the lines lV-JV and V, respectively, of Fig. 3.

Fig. 6 is a view similar to Fig. 3, showing a further modification oi the invention.

Fig. '7 is a sectional plan view in the plane of the line VHVII 01 Fig. 6.

Fig. 8 is a tragmental sectional elevation of another modified form of electrical heat ing appliance embodying features of the present invent-ion.

Fig. 9 is a sectional elevation in the plane of the line IXIX of Fig. 8.

Fig. 10 is a view similar to Fig. 8, showing a modified form of the type of heating unit disclosed therein.

Fig. 11 is a sectional elevation in the plane of the line XIXI of Fig. 10.

In Fig. 1 of the drawings. there is disclosed a radiant heater of the bowls. aped reflector type. The body portion of the r flector, indicated at 11, may be considered as of the ordinary parabolic type having a central aperture in which a socket 12 of insulating material is secured, this socket having a flange 13 at its inner end bearing against the inner wall of the reflector. The socket 12 is held in position by means of a nut ll threaded on the rearwardly projecting portion of the socket and bearing against the outer wall of the reflector. A metallic screw shell or busln ing 15 is fixed in position within the socket 12. as by being threaded into a cooperatively threaded portion of the wall of the socket, an extension 16 on the shell 15 being secured in position by a screw 17 which passes through the rear wall of the socket, being held in place by a securing nut and also serving as a means for connecting the conductive sh ll 15 to a line terminal. A contact 18 has an apertured extension through which a connection screw 19 passes, this screw passing through the rear wall of the socket. being held in place therein by a. securing nut and serving to maintain the contact 18 in operative position and also acting a. a line terminal connection.

A plug 21 includes an insulating body having a. conductive and externally threaded metal shell fixed thereon and adapted to be threaded into the conductive shell 15 so as to thereby hold the plug in operative position. The upper edge of the shell 22 has a bent-over portion 23 disposed on a ledge formed by providing a slot at the outer side of the plug 21. as shown. A bolt or screw 25 having a head 26 is disposed in an axial bore of the plug 21, a securing nut 27 being mounted in operative position on the inner end of the screw at the rear end of the plug.

The bolt or screw 25 disposed in the axial bore of the plug 21 has its head 26 formed as,

or has conducti'vely connected to its head, as

by welding, a contact piece provided with a recess or cavity adapted to receive a terminal end of a rigid and self-sustaining heating resistance element 28. This resistance heating element 28 is preferably a unitary, self-sustaining, molded and heat-hardened composition product wherein a carbonaceous material, such as silicon carbide, is the principal constituent. Certain heating elements of the preferred character are well known in the art, the same being composed of silicon carbide as an essential constituent, with or without one or more modifying substances for altering mechanical or electrical characteris tics of the final resistance element. Likewise, this resistance element is preferably such as has its end or terminal portions considerably more highly conductive than the body portion of the element, and consequently less liable to heating such as might have a deleterious etlectupon the metallic contacts associated with the terminal portions of the resistance element.

This resistance element 28 is disposed in substantial alincment with or symmetrical with respect to the axis of the socket 12 and the reflector 11, the other terminal end of the heating element being disposed in a recess formed in a contact piece 32 of conductive material, preferably material, such as aluminum, or an iron-chromium alloy, such as Ascoloy, which is highly resistant to the effects of high temperatures. The use of aluminum as a contact material for silicon carbide resistors is disclosed and claimed in my copending application, U. S. Serial No. 386,- 979, filed August 19, 1929. This contact piece is attached, preferably by welding or riveting, to a relatively stiff and resilient mounting of conductive material in the general form of an elliptical or bowed spring 34, preferably of tempered steel or other conductive and resilient material, such as a suitable bronze or monel metal. This spring element has its inner ends apertured and arranged in overlapping relation beneath the head 26 ot the bolt 25 and is insulated therefrom by a flanged insulating bushing 35, the bolt 25 passing through the bushing arranged within the alincd apertures in the ends of the bowed element 34 and serving to maintain these end portions fixed. as within a recess formed between side walls or projections at the end of the plug 21, and to maintain the parts generally in desired permanent relation when the securing nut 27 is secured in operative position.

\Vith the parts in this condition, a circuit is established from terminal screw 17, through the metal shell 15, metal shell 22 and its bent-over end 23, terminal ends of the spring mounting 34, and through the two side arms of the latter in parallel, to the contact piece 32, through the heating element 28, contact piece 26, screw or bolt 25, and spring contact 18, to the terminal screw 19. The contact pieces, or surface portions thereof,

26 and 32 are preferably of aluminum where the operating temperatures are not too high, and of Monel metal or iron-chromium alloy, as Ascoloy, for higher temperatures. The cavities or recesses in the contact pieces 26 and 32 are of such size and shape, preferably more or less conical in shape, as to readily receive the terminal ends of the heating element 28 and insure effective yielding mechanical and electrical engagement and support through butt-end contact between the material of these contact pieces and the terminal ends of heating element.

Vith the parts arranged as described and a suitable design of the bowed spring element 34 to strength and resiliency, this spring element exerts the desired and required pressure upon the terminal ends of the heating element 28 in the direction of its longitudinal axis to maintain the same in desired operative position, with the terminal portions thereof in secure mechanical and electrical engagement with the contact pieces 26 and 32, through butt-end engagement therewith. Obviously, the cross-sectional area of the spring mounting 34 is such that no appreciable heat is generated in this portion of the electrical circuit; and the resilient body portion is sufliciently removed from heating element 28 so that the mounting retains the required resilience and holding effect during operation.

In order to remove or replace the resistance element 28, the bowed spring element 34 is distorted by transverse pressure thereon, to more or less the shape indicated indotted outline; and under these latter conditions, the resistance element 28 may be readily removed or a replacement element inserted to operative position; and the bowed spring element can then be permitted to return to normal position indicated in full lines, wherein it is effective to support and maintain the heating element in electrically and mechanically satisfactory and efficient operative position.

In accordance with Fig. 2, the invention is embodied in a heating appliance adapted for use in the manner of the ordinary radiant reflector type heater designed for domestic use or as a device for applying heat for therapeutic purposes. An insulating socket 46 having a body portion similar to that of the socket 12 of Fig. 1 is secured in av suitable manner to the reflector 47 of ordinary suitable shape as by a spring clamping flange 48 on the reflector being held in securely clamped relation in a recess 49 on the ex- ,srior of the socket 46. This socket 46 has secured therein the conductive screw shell 16 held in position in the socket and having a terminal portion connected to a terminal screw as indicated in Fig. 1. The insulating plug 51 is provided with a conductive screw shell 52 which engages in firm but detachable threaded relation with the screw shell 16; and the plug is provided at its lower side with a central contact 53 which is adapted to engage with a spring contact held in place and connected to a line terminal in the man ner of the central contact on the bolt 25 and the corresponding spring contact 18 and line terminal screw 19 of Fig. 1.

Connected to the conductive screw shell 52 and the central contact 53, these parts constituting the circuit terminals of the removable plug, are conductive spring jaws or contacts 54 and 56, respectively, these jaws being mounted in recesses in the plug 51, and detachably engageable by contact blades or fingers 57 and 58, respectively, in such a manner as to insure the holding of the latter in mechanically and electrically secure position. These contact fingers 57, 58 are provided with portions extending in opposite directions and at right angles to the portions in engagement with the contacts 54 and 56, these oppositely extending portions being provided adjacent their outer extremities with concave or re cessed contact portions 59. The recessed contact portions 59 receive in butt-end contact engagement the approximately spherical or otherwise curved ends of the resistance heating elements 28a and 286, the correspondingly formed upper ends of the latter being maintained in like engagement within similarly formed recessed contact portions 61 of a bridging conductive cap 62. This cap 62 is maintained in suitable operative position wherein its contact portions are yieldingly urged against the upper ends of the heating elements 28a, 286, by resilient spring arms 63 of generally bowed formation, having their upper ends attached by screws or the like to turned down side pieces of the terminal cap 62, the lower ends being integrally formed to present a flat securing portion fixedly mounted in operative position on the end of the plug 51 by screws passing through the flat securing portion and into anchoring pieces or portions secured to the plug 51. The arrangement indicated, wherein the heating units are arranged symmetrically about the axis of the supporting plug 51 and are inclined slightly toward each other is a desirable one. While the contact parts 54, 57 and 56, 58 are described as separable, these parts may be integral and fixedly mounted on the plug 51.

With the parts in the position indicated, the circuit through the appliance may be traced from the central contact 53, through spring contact jaw 56 and its cooperative contact linger 5S, heating element 28a, bridging contact cap 62, heating element 28?), contact linger 5?, spring contact jaw 5st, and conductive shells 52 and 16, to the otl er terminal ot supply circuit. While the arrangement shown provides for the connection of the heating elements 28a and 28?) in series, provisin i be made for connecting these elements in parallel across the supply line by having both oi the spring contact jaws and 56 connected to the conductive screw shell 52 and the central contact 58 con ected to the intermediate connecting portion of the resilient arms 03. l l i h these latter connections, the current entering through the cen tral contact 53 passes through the arms 63, to the bridging contact and thence through the two heating elements 28a, 2871 and the lower contact mountings therefor in parallel, to the conductive shell 52.

As will be apparent from the disclosure to Fig. 1, one or more of the heating elements 28o, 286 may be removed from operative position after resilient arms 0?; have been squeezed or forced toward each other to raise the bridging contact 02, at which time the terminal portions of the heating elements may be readily removed from the contact recesses 59 and 61. lVith this explanation, the method of replacing a heating element in operative position will be apparent.

The resilient.- spring arms may be suiticiently resilient and yielding to detachably secure the heating elements in operative position without the necessity for any yielding action of the bent-over contact portions of the contact fingers 5?, 58, in which case the latter may be rigidly secured in operative position; or the support 63 may be relatively rigid, with the bridging contact 62 thus held in delinite position, and all of the necessary yielding of the contact portions to permit removal and replacement of the heating elements may be secured through yielding of or spring etfeet in the contact parts 57, 58.

In the heating appliance disclosed in Figs. 3, l and 5, the insulating socket 16 is held in operative position in the axial aperture in the reflector ll" in the manner indicateo in connection with Fig. 2, and it may be desirable to provide the t ange 48 with clamping projections adapted to secure the tightening of the flange about the socket, in the recess 49 thereof. As indicated, an insulating plug '6'? is provided with a conduct've screw shell 68 adapted to engage the screw shell 16 in threaded relation. The upper surface of the plug is formed with alined recesses 69 separated by a raised portion 71, the recesses and the raised portion being arranged substantially along diameters at i ght angles to each other. Bent or bowed spring terminals 72, 73 are arranged with their lower flat portions 74; disposed in the recesses 69, spaced and substantially parallel upper portions 7 5 of these spring contacts being provided at their upper sides with contactstrips 76 each provided with a recessed contact portion 78 adjacent its inner end. The contact spring 73 is held in position in its recess (59 by the screw bolt 79 which p sses through the insulating plug and an apcrtured extension of the screw shell 68, a nut on the lower end of the bolt 79 securing the parts in operative position and maintaining the desired electrical connection between the shell 08 and the bolt 7 9 and contact spring "2'3. The contact spring 72 is held in operative position and connected to the other electrical terminal of the plug 67 by a screw or bolt 81 having its lower end threaded into a connection or anchoring piece 82, the latter ha *ing threaded therein the upper end or a bolt 83 whose h ad constitutes a contact terminal 8% for the plug, this latter contact being adapted for engagement with a spring contact 18 secured to a connection screw or terminal 19, arranged as in Fig. 1 or Fig. 6.

()n the projection 71 at the upper side of the plug 67, there is mounted the flat intermediate portion 86 which serves as a connection or support for the two bowed spring terminals S7 and 89. the upper portions of the latter being provided with contact strips 76 and recessed contact portion 78, similar to corresponding parts of the spring terminals 72 and 73. A plurality of detents formed in the intermediate portion 86 of the spring terminals 8? and 89, these detents being indicated at 91, cooperate with recesses in the raised portion 71 to definitely determine the position of the portion 86. The contact springs 87 and 89 are definitely secured in operative position by a pedestal or supporting post 93 disposed in substantially axial alinement with the axis of the plug 67 and having a shoulder 94 cooperative with the upper side of the intermediate spring contact portion 86 and a reduced lower end 95 passing through an aperture in the plug and secured in position by means of a nut threaded on the lower end of the post 93, the plug being of such two-part construction as will permit definitely securing this pedestal 93 in operative position prior to the final assembly of the contact springs and their terminal securing means.

A cap 96 provided with a. central threaded hub is mounted, as by threading, on the upper end of the pedestal 93. This cap is provided with an overhanging flange 97 within which are disposed a plurality of bridging contact members insulated from each other and also insulated from the cap 96 by a suitably formed spacer of insulating material. indicated at- 98. These bridging contact members, indicated at 101 and 102, are similarly formed, cachbeing provided with a plurality of recessed contact portions 103 spaced to an appreciable extent but nevertheless connected electrically through the material of the contact members. The cap 96 and the contact elements carried thereby are suitably held in desired adjusted position on the pedestal 93 by means of a nut 104 disposed below the contact elements 101 and 102 and having supporting and insulating spacing washers interposed between the adjustable nut and the contact elements. It will be apparent that with the nut 104 in a definite position on the pedestal 93, the cap 96 and the parts carried thereby may be threaded down on the pedestal until such parts firmly bear upon the washers carried by the nut 104.

Similar resistance heating elements 28a, 28?), 280 and 2803 are disposed in operative position between the spring terminals 72, 73, 87 and 89 and corresponding recessed con tact portions of the bridging contact elements 101 and 102. These heating elements are preferably of the type having somewhat rounded and more highly conductive ends which have substantial engagement, through butt-end contact, within the contact recesses 78 of the spring terminals and the contact recess 103 of the bridging contact 101 and 102. As indicated, with the bridging contact elements 101, 102 held in fixed position, and the contact terminals 72, 73, 87, 89 of suitable design as to strength and resilience, the latter contact terminals electrically and mechanically engage the lower ends of the heating elements with suificient pressure to securely but still yieldingly retain the heating elements in mechanically operative position and desired electrical engagement between the contact springs and the upper bridging contacts. It will be apparent that this yielding efiect of the contact springs is such as permits ready removal and replacement of any heating element, as desired.

The sizes of the heating elements and the lower contact springs therefor will determine to a great degree the required resilience of the contact springs, and hence the amount of permissible yielding or depression of the upper portions of these contact springs that may be permissible.

In the specific arrangement disclosed herein, the four heating elements are connected in series circuit between the terminals 84 and 68 of the plug 67, the connection of these terminals to a line circuit, through the terminal screws 17 and 19 of Figs. 1 and 6 being apparent. The circuit may be traced from the contact shell 68, through bolt 79, contact spring 73, heating element 28?), bridging contact 102, heating element 28d, contact spring 89, contact spring 87, heating element 280, bridging contact 101, heat ing element 28a, contact spring 72, bolt 81, connection piece 82, and terminal screw 83 with its terminal head 84. It will be apparent that with slight modification, that is, connecting the terminal screw 83 to the reduced portion 95 of the pedestal 93, and connecting the bolt 81, independently of the bolt 83 (disconnecting 81 from 83), to the conductive shell 68, the heating elements may be connected in series-parallel arrangement, as will be apparent by tracing the modified circuit from terminal 84 through the two parallel branches, with their connecting bolts 79 and 81, to the conductive shell 68.

In the form 01 the invention disclosed in Figs. 6 and 7, the insulating socket with its terminals is mounted in the reflector 47 in a manner that will be apparent from the description hereinabove as to the other figures. Likewise, the insulating plug 67 is detachably secured in operative position in a previously described manner. However, the present heating appliance includes only two heating elements 28a, 28?), the lower ends of these heating elements being in desired mechanical and electrical engagement with the contact portions of the spring terminals 72and 73 which are secured in position in essentially the same manner as the corresponding parts of Fig. 3. The upper holding arrangement is somewhat different from that shown in Fig. 3. In the present case, a securing cap 105 is adjustably threaded on the upper end of the central pedestal 93, an annular and centrally apertured bridging contact 106 being held in position between the lower side of the cap 105 and the adjustable nut 104 on the pedestal 93, this bridging element 106 being insulated from the pedestal 93 or not, as desired. The bridging contact element 106 is formed with recessed contact portions 107 within which the rounded upper ends of the heating elements 28a, 28?) engage with the desired mechanical and electrical en gaging-pressure. The supporting pedestal 93 is preferably mounted in position on the insulating plug 67 through the intermediary of a collar 108 upon the upper surface or" which the shoulder formed on the pedestal engages, the reduced portion 95 of the pedestal passing through the collar and a suitable aperture in the insulating plug, being secured in operative position in the manner described in connection with Fig. 3.

t will be apparent that the heating elements 28a and 287) are connected in series between the terminal screw 83, connected to line terminal 19, and terminal bolt 7 9 which is connected to the conductor shell 68 and thence through a shell 16 to the terminal 17.

However, it will be apparent that with a corresponding modification of the terminal arrangements for the connecting bolts 79 and 81 and the reduced portion 95 of the pedestal 93, such as is described in connectionwith Fig. 3, the two heating elements 28a, 286 may be connected in parallel between the line terminals.

In accordance with the disclosure of Figs.

8 and 9, features of the invention are applied to a heating appliance especially adapted for purposes of heating liquids in a container. A container or receptacle 109 is provided with an aperture in which a tubular element 110 having a closed inner end, is secured in fluid tight relation, preferably by welding an external flange 112 at the open end of the receptacle 110 about the edges of the apertured wall of the container 109. A base or support of insulating material 113 has a guiding and fairly close fit in the outer or open end of the tubular receptacle 110, this base or ipport being detachably secured in operative position, preferably by scrtws passing through a flange on the support and into threaded apertures in the flange 112 on the element 110.

A bent-over or bowed terminal spring 11 1 is mounted at the inner side of the supporting plug 113, a relatively flat portion 115 being secured against the inner side of the plug and held in operative posi ion by one or more connection screws or bolts 118. By utilizing a detent near the lower end of the flat portion 115 cooperative with a recess in the plug 113, one termina or connection screw 118 will suflice. The free end of the terminal spring 114 is provided with a contact strip 116 having a recessed contact portion 117 for the reception of the rounded end of a heating element 28.

An insulating block 119 is disposed at the inner closed end of the tube 110, this block having a fairly close guiding fit with the walls of the tube and being secured to and maintained in desired spaced relation with respect to the insulating plug 113 by a plurality of supporting rods or bolts 120, the latter being adjustably secured in the plug 113, by nuts engaging opposite sides of the plug. The inner ends of these rods or bolts 120 are rigidly secured to the support 119 in such a manner that the support is readily removable from the tube 110 along with the plug 113. At the outer end of one or both of the rods 120, there is provided a bridging connection 121, preferably set within a recess at the outer side of the plug 113, extending to the terminal screw or bolt 123. As indicated, a collar is disposed on the bolt 123 between the bridging element 121 and a securing nut 12%. If desired, this same type of collar may be disposed upon the end of the rod 120 between the bridging element 121 and the securing nut on the end of the rod. A terminal cap 126 is held in position on the side of the support 119 adjacent the plug 113, this cap being preferably held in position by the inner ends of the rods 120 and the securing nuts thereon, in a manner more particularly shown in connection with Fig. 10 hereinafter. A recessed contact portion 127 is formed in the terminal cap 126 for the reception of the rounded end of the heating element 28 whose other end is maintained in desired mechanical and electrical engagement in the recessed contact portion of the terminal spring 11.

As has been described, the insulating sup port 113 may be removed from operative position in the tubular element 110, the mechanical mounting of the heating element 28 being such as to insure that the latter remains in operative position when the parts are withdrawn from the tube 110. In fact, the insulating support 113 and its inner guiding element 119, along with the heating element 28 may be readily handled as a unitary device, the heating element 28 being so mounted in position as to insure its safety during any ordinary handling. It will be apparent that the circuit through the heating element is from the connection screw 118, through spring terminal 11%, heating element 28, terminal cap 126, supporting rod 120, bridging element 121, to connection screw 123.

In the modification shown in Figs. 10 and 11, the essential features of mounting the tubular element 110 in a liquid containing vessel 109 are essentially the same as in Fig. 8; and likewise, the inner guiding support 119s of Fig. 10 is secured in operative position or mounted upon the insulating support 113 in essentially the same manner as has been described in connection with Fig. 8, any material differences being possibly in the matter of attaching the outer ends of the supporting rod 120 directly to the body of the support 113. A plurality of terminal springs 11 1a and corresponding heating elements 28a, 28?) are mounted in operative position substantially symmetrically disposed with respect to the axis of the insulating support 113 and the tubular element 110. The terminal cap 126a is provided with two symmetrically arranged recessed portions 127 for the reception of the ends of the heating elements 28a, 28?), the element 126a serving as a b idge between the terminals of these two elements.

The normal circuit may be from terminal screw 118a, through spring terminal 114a, heating element 28a, bridging contact 126a, heating element 28b, terminal spring 114]), to terminal screw 118b, an arrangement which connects the heating elements in series. However, by utilizing the ends of one or both of the supporting rods 120 as a terminal connected to one side of the supply line, with the connection screws 118a and 118?) connected to the other terminal of the line, the. two heating elements will be connected in parallel between the terminals of the supply line.

A satisfactory material for the contact springs which are required to have sufiieient resilience to yieldingly maintain the heating elements in operative position, is atempered bronze or monel metal; and for the contact strips or other portions which are in immediate contact with the ends of the heating elements, aluminum for the lower operating temperatures, and an iron-chromium alloy, such as Ascoloy, for the higher operating temperatures are quite satisfactory. The several materials mentioned for these purposes of heat resistance coupled with resilience and ability to maintain themselves without destructive oxidation or deterioration may be selected depending upon the required operating temperatures. However, in this connection, it is of great advantage to utilize a heating element of the character described hereinabove and in applicants copending cases wherein a heat-hardened substantially non-metallic heating unit is essentially composed of silicon carbide, with or without modifying elements and having ends of increased conductivity, an especial eiiect of these highly conductive ends being to retain the metallic contact parts associated therewith at satisfactory operating temperatures.

It will be apparent that in accordance with this invention, a heating appliance is provided embodying one or more self-sustaining heating elements of the cartridge type which are yieldingly and detachably held in operative position upon a support in such a manner as to permit handling of the support with the heating elements mounted thereon,

the combination constituting a unit which may be readily inserted in or removed from a reflector or other carrier.

It should be understood that it is not desired to limit the invention to the exact details of description shown and described, for obvious modifications may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patent:

1. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal contacts carried by said support, a resilient compressible looped member whose base is clamped between said insulating support and one of said contacts with the aid of a block which insulates said contact from said resilient member, the opposite free end of said loop carrying another contact, and a self-sustaining resistance heating element mounted between said contacts by means of said looped member.

2. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal contacts carried by said support, a resilient compressible looped member whose base is clamped be tween said insulating support and one of said contacts with the aid of a block which insulates said contact from said resilient member, the opposite free end of said loop carrying another contact, and a self-sustain ing resistance heating element yieldingly and detachably mounted between said contacts by means of said looped member.

3. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal contacts carried by said support, a resilient compressible looped member whose base is clamped between said insulating support and one of said contacts with the aid of a block which insulates said contact from said resilient member, the opposite free end of said loop carying another contact, and a self-sustaining resistance heating element yieldingly and detachably mounted between said contacts through butt-end engagement of the ends of said heating element with said terminal con tacts by means of said looped member.

4:. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal contacts carried by said support, a resilient compressible looped member whose base is clamped between said insulating support and one of saidL contacts with the aid of a block which insulates said contact from said resilient member, the opposite freeend of said loop carrying another contact, one of said contacts being yieldable, and self-sustaining resistance heating element yieldingly and detachably mounted in operative position between said contac lzrough butt-end engagement between said contacts and the extreme ends of said heating element by means of said looped member.

5. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal. contacts carried by said support, one of said contacts being located adjacent said support, another of said contacts being substantially spaced from said support, one of said contacts being yieldable, and a self-sustaining resistance heating element having its ends of greater specific conductivity than its body portion, said heating element being yieldingly and detachably mounted in operative position between said terminal contacts through engagement between said contacts and the extreme ends of said heating element.

6. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal contacts carried by said support, certain of said contacts being located adjacent said support and others of said contacts being electrically connected together and spaced from said support, certain of said contacts being yieldable, and a plurality of self-sustaining resistance heating elements yieldingly and detachably mounted between pairs of said contacts.

7. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal contacts carried by said support, certain of said contacts be ing located adjacent said support and others of said contacts being electrically connected together and spaced from said support, certain of said contacts being yieldable, and a plurality of sclt-susraining TQSlH 'QEICQ heating its yieldingly a: d ily unilml elcmer a L between pairs ot said contacts throngn butt end engagement of the l of said heating elements with said =1 contacts.

8. In an electrical in it of said contacts leing electri alu together and spa ed from said support, cerbeing yieldable, and a aininir resistance heatw ends or greater conduc neir ody p rt nd yield in; detacnabl nioun a operative position between pa rs of said terminal contacts through butt-end eng "(:21 en be tween said contacts and the ends or" Still heating elements.

9. In an electrical heatinit combination with an insul. plurality of spaced terminal ried by said support, cert in Yd contac being located adjacent said support and others of sa d contacts being electrically connected tog er and spaced tron said support, (Ql'tlllll of said contacts being yield, ble. and plu 'ality of selt-sustainin g resistance heating elements yieldingly and detachably mounted between pairs of said contacts through butt-end engagement of the ends of said l eating elements with said terminal contacts, said heating elements being symmetrically disposed about the axis of said support.

10. it adiant energy generating unit conr prising an insulating base, a supporting post projecting from the base, a yoke carried by the poslx a plurality of current conducting spring clips carried by tl e base a nd insulated from the post, energy converting elements supported between the yoke and the clips, and electrical terminals carried by the base and connected to the clips.

11. it therapeutic radiant energy generating unit comprising an insulating base provided with inner and outer plug-receptacle contacts, supporting post projecting from the base, a current conducting yoke ca 'ried by the post, a pair of current conducting spring clips carried by the base on opposite sides of the post, an energy converting element supported by and between each clip and the yoke, and electrical conductors for connecting the clips to the plug-receptacle contacts whereby current may be conducted to and from the energy converting elements.

12. In an apparatus for supplying radiation from a rigid massive source which is heated to a substantially uniform tempera ture throughout, a bowl-shaped reflector, an insulating support detachably mounted upon said reflector, a plurality ii spaced terminal contacts mounted upon said support, one oi. said contacts being locat-cnl adj accnt said support and adjacent to the aXis ot the r doctor, another of said contacts being displaced from said first contact along the axis of the reflector, one of said conta'ts being yield able, and rigid massive electrical re. -stor yieldingly and detachably mounted between id contacts in such 1: ion that the resistor one may be removed Without. removing its rapport.

13. In an apparatus for supplying radiation from a rigid massive source which is heated to a substantially uniitorn'i temperature thrtmghout, a carrier, an insulating support dctachably mounted upon said carrier, a plurality of spaced terminal contacts mo mtcd Sit i ll 1 upon said supp r;-, one of said conloxated adjacent said support, in onta be'ng disposed from t a snliiciont distance to include r betw en he contacts, one 'ng yieldable, and a rigid oer.

yeldably and deta:hably mounted bowie-c: said contacts so that the resistor may be removed alone Without rein -ring its terminal connections.

fit 1' rod o,

'i-l. in an apparatus ior supplying radiation from a pin 'ality of rigid mas es which we heated to a substantialy uniform temp. tl .yh jut a retlector, an. insulatii ly mo mted upon said re ubstant-ially coincident n lei a pin 'ality 0t said support, certain ot said contacts being located adjacent said support, others of said contacts being electrically connected together and dislaced from said support along the axis of said reflector, certain of said, contac is being yieldablo, an d a plurality of self-sustaining resistance leating elen'ientn yieldingly and detachably mounted in operative position through butt-end engagrenunt with pairs of said terminal contacts wherelnz the resistors alone may be removed Without removing their tern'iinal connections. 7

15. The appa'atus de c ibed in claim ll in which the resistors are symmetrically distributed about the ax: ot the reflector.

1(. In an apparatus for supplying radiation -lrom a rigid ma. re source which is heated to a substantianr uniform temperature throughout, a rei' ector, insulating support, said insulatir support being de tacl ably mounted on said retl ctor with its axis in substantial alignment with that of said reflector, a plurality of spaced terminal contacts carried by said support, one of said contacts being located adjacent said support, another of said contacts being spaced from said support, means carried by and syn'imetrically disposed about the axis of said support for mounting said latter contact in n all position, one of said contacts being yieldable, and a rigid massive resistor yieldingly and detachably mounted in operative position be tween said contacts through frictional buttend engagement between said contacts and the ends of said heating element, whereby the resistor alone may be removed without removing its terminal connections and supports.

17. In an electrical heating appliance, in combination with a base, a plurality of spaced terminal contacts carried by said base, one of said contacts being located adjacent said base, another of said contacts being substantially spaced from said base, means for mounting said latter contact in position, said means comprising a plurality of arms supported by said base and disposed symmetrically about the axis thereof, one of said contacts being yieldable, and a self-sustaining resistance heating element yieldingly and detachably mounted in operative position between said contacts through butt-end engagement between said contacts and the extreme ends of said heating element.

18. In an electrical heating appliance, in combination with a base, a plurality of spaced terminal contacts carried by said base, one of said contacts being more remote from said base than another, a plurality of yielding conductive arms carried'by said base and serving as a resiliently yieldable mounting for said latter contact, and a self-sustaining resistance heating element having its ends of greater conductivity than its body portion, said heating element being yieldingly and detachably mounted in operative position be tween said terminal contacts through engagement between said contacts and the extreme ends of said heating element.

19. In an electrical heating appliance, in combination with an insulating base, a plurality of spaced terminal contacts carried by said base, certain of said contacts being located adjacent said base and others of said contacts being electrically connected together and spaced from said base, means carried by said base for resiliently supporting said latter contacts, and a plurality of selfsustaining resistance heating elements symmetrically disposed about the axis of said base and yieldingly and detachably mounted between pairs of said contacts through buttend engagement of the ends of said heating elements with said terminal contacts;

20. In an electrical heating appliance, in combination with an insulating base, a plurality of spaced terminal contacts carried by said base, certain of said contacts being located adjacent said base and others of said contacts being electrically connected together and spaced from said base means comprising a plurality of spaced arms symmetrically disposed about the axis of and supported by said base for yieldingly mounting said latter contacts in position, and a plurality of self-sustaining resistance heating elements yieldingly and detachably mounted between pairs of said contacts through butt-end engagement of the ends of said heating elements with said terminal contacts, said heating ele ments being symmetrically disposed about the axis of said base.

21. In an electrical heatingappliance, in combination with a carrier, an insulating support detachably mounted upon said carrier with its axis substantially coincident with the axis of said carrier, a pluralityof spaced terminal contacts carried by said support, certain of said contacts being located adjacent said support, others of said contacts being electrically connected together and spaced from said support, means comprising a plurality of spaced arms carried by said support and symmetrically disposed about the axis thereof for mounting said latter contacts in position, certain of said contacts being yieldable, and a plurality of self-sustaining resistance heating elements arranged symmetrically about the axis of said support and yieldingly and detachably mounted in operative position through butt-end engagement with pairs of said terminal contacts.

22. In an electrical heating appliance, in combination with a carrier, aninsulating support detachably mounted upon said carrier with its axis substantially coincident with the axis of said carrier, a plurality of spaced terminal contacts carried by said support, certain of said contacts being located adjacent said support, others of said contacts being electrically connected together and spaced from said support, means comprising a plurality of spaced resilient arms carried by said support for mounting said latter contacts in position, and a plurality of self-sustaining resistance heating elements yieldingly and detachably mounted in operative position through butt-end engagement with pairs of c yieldingly and detachably mounted in operative position between said recessed contact portions through frictional butt-end engagement between said contact portions and the ends of said heating element.

24. In an electrical heating appliance, in combination with an insulating support, a plurality of resilient terminal contacts carried by said support and having recessed contact portions, a bridging terminal spaced from said support, means comprising a plurality of spaced resilient arms symmetrically disposed about the axis of said support for mounting said bridging terminal in operative position, and a plurality of self-sustaining resistance heating elements yieldingly mounted in operative position between the recessed portions of said contacts and said bridging terminal, said heating elements being arranged symmetrically about the axis of said support.

25. In an electrical heating appliance, in combination with an insulating support, a plurality of spaced terminal contacts carried by said support, certain of said contacts being located adjacent said support and others of said contacts being electrically connected together and yieldably mounted at a point spaced from said support, a resilient deformable member to provide said yicldable mounting of the spaced contacts, and a plurality of self-sustaining resistance heating elements each disposable between one of said adjacent contacts and one of said remote contacts, said elements being immediately removable and insertible on slight distortions of said resilient member.

26. In an electrical heating appliance, in combination with a carrier, an insulating support detachably mounted upon said carrier, a plurality of spaced terminal contacts mounted upon said support, one of said contacts being located adjacent said support, another of said contacts being substantially spaced from said support, means comprising a plurality of spaced arms carried by said base and symmetrically disposed about the axis of said base and said carrier for mounting said latter contact in position, one of said contacts being yieldable, and a self-sustaining resistance heating elementyieldingly and detachably mounted between said contacts through frictional butt-end engagement between said contacts and the ends of said heating element.

In Witness whereof I affix my signature hereto.

HAROLD N. SHAIV. 

